Degradation Of Metformin,Iopamidol And Sodium Diatrizoate By High-intensity UV/Sulfite System

Metformin,Iopamidol and Diatrizoate are typical substances in water PPCPS（Pharmaceutical and Personal Care Products,drugs and personal care）,have received the environment in recent years.There are more and more attention in the field.They have a stable chemical structure and the existing treatment technology of sewage plants is difficult to remove,leading to a large amount of water in various water conditions,threatening the natural environment and human health.Therefore,it is urgent to establish a safe and efficient degradation technique for in-depth treatment.In this thesis,using metformin,iopamidol and diatrizoate as the target pollutants,a high-intensity UV/sulfite advanced reduction system was constructed.The effect of initial p H,initial concentration of target pollutants,sulfite dosage,light intensity,concentration of coexisting substances on the degradation efficiency of target pollutants was investigated.Influence of metformin denitrification and deiodination effects of iopamidol and diatrizoate.The case of free radicals in the reaction system was investigated by free radical suppression test,and finally the degradation product of each target contaminant was measured,and the degradation path of the target contaminant was analyzed.The following conclusions were obtained:（1）UV/sulfite interaction can effectively degradate metformin and denretize its nitrogen,and individual ultraviolet irradiation with alone,no degradation.With the p H=9,the metformin concentration was 15 mg/L,the sulfite concentration was 10 mmol/L,and the Met was reacted for 30 minutes under the conditions of 100%,and the metformin was as high as 96.54%.Too high and too low p H are not conducive to the degradation of metformin.When other conditions,the preferred degradation of metformin is 8.The concentration of the right amount of raised sulfite can increase the degradation effect of metformin.The degradation rate of metformin is elevated as the light is enhanced.In addition,humic acid has a strong inhibitory effect on the degradation of metformin,and the trace amount of HCO₃^-can promote the reaction,but as HCO₃^-concentration gradually increases,the promotion is gradually weakened.In free radical inhibition experiment,potassium nitrate is better than sodium nitrite.The addition of methanol and t-butanol have almost no effect on degradation.Therefore,it can be inferred that e_aq^-is a major free radical that causes metformin degradation in this system.Finally,the degradation product of three dimethyloids was obtained,and the degradation method was fed by the C-N bond caused by e_aq^-attack.（2）UV/sulfite interaction with individual ultraviolet irradiation can effectively degrades iopamidol and deiodine it,while the sulfite has no degradation of iopamidol.However,the ultraviolet irradiation effect is poor and cannot produce e_aq^-that can accelerate iopamidol deiodal effect.At p H=9,the iopamidol concentration was 50μmol/L,the sulfite concentration was 500μmol/L,and the degradation rate of iopamidol was as high as 100%of iopamidol after 5 minutes of 100%.As p H increase from 6 to 10,iopamidol degradation rate and deiodalization rate also increase,but the effect of p H=9 and p H=10 is not very different.The appropriate amount of increased sulfite concentration can increase the degradation effect and deiodalization rate of iopamidol.At the same time,the degradation rate and the deoddin ratio of iopamidol decrease with the decrease of the light intensity.The coexistence substances in the water such as humic acid,HCO₃^-,and the like show a certain inhibitory effect.Free radical suppression tests can infer except for ultraviolet direct fluid,e^-_aqis a major free radical resulting in iopamidol degradation.Finally,the degradation product of eight iopamidol is obtained,and the degradation method includes e_aq^-attack and direct photolysis caused by direct fluid solution.（3）UV/sulfite interaction with individual ultraviolet irradiation can effectively degrade the diatrizoate and deiodize it,while the addition of sulfite alone has no degradation effect on diatrizoate.But UV irradiation alone degrades slowly,and e_aq^-to speed up the diatrizoate deiodide efficiency.At p H=9,diatrizoate at a concentration of 40μmol/L,the sulfite concentration was 500μmol/L,and the diatrizoate degradation rate was as high as 99.18%after 150 seconds of 100%.The degradation rate of the flue-shadd sodium is elevated as the p H 6-10.The amount of increased sulfite can increase the degradation effect of diatrizoate.Further,the degradation rate and the deoddes of diatrizoate decrease with the decrease of the light intensity.Coexistence materials such as humic acid,HCO₃^-degradation and deiodal of sodium inhibitory effect showed a certain inhibitory effect.Radical inhibition experiments showed that,in addition to UV photolysis,the degradation of diatrizoate was dominated by e^-_aq.Finally,four degradation products of diatrizoate were obtained by measurement,and the degradation methods included the attack of e_aq^-and the direct photolysis-induced deiodination substitution and the formation of heterocycles.